It is obvious, from the foregoing analyses, that great differences must exist in the manurial value of the urine of different animals. Not only do they vary greatly in the proportion of solid matters which they contain, but also in the kind and quantity of their nitrogenous constituents. They differ also in regard to their saline ingredients; and while salts of potash and soda form the principal part of the ash of the urine of the ox, sheep, goat, and horse, and phosphoric acid and phosphates are entirely absent, that of the pig contains a considerable quantity of the latter substances, and in this respect more nearly resembles the urine of man. Human urine is also much richer in urea and nitrogenous constituents generally, and has a higher value than any of the others. It is especially worthy of notice that the urine of the purely herbivorous animals (with the exception of the sheep, which contains a small quantity), are devoid of phosphates and urea; and consequently, when employed alone, they are not general manures--a matter of some importance in relation to the subject of liquid manuring, which will be afterwards discussed. _Dung._--The solid excrement of animals is equally variable in composition. That of the domestic animals which had the ordinary winter food was found to have the following composition:-- Horse. Cow. Sheep. Swine. Per-centage of water in the } 77.25 82.45 56.47 77.13 fresh excrement } Ash in the dry excrement 13.36 15.23 13.49 37.17 100 parts of ash contained-- Horse. Cow. Sheep. Swine. Silica 62.40 62.54 50.11 13.19 Potash 11.30 2.91 8.32 3.60 Soda 1.98 0.98 3.28 3.44 Chloride of sodium 0.03 0.23 0.14 0.89 Phosphate of iron 2.73 8.93 3.98 10.55 Lime 4.63 5.71 18.15 2.63 Magnesia 3.84 11.47 5.45 2.24 Phosphoric Acid 8.93 4.75 7.52 0.41 Sulphuric acid 1.83 1.77 2.69 0.90 Carbonic acid ... trace trace 0.60 Oxide of manganese 2.13 ... ... ... Sand ... ... ... 61.37 ---- ---- ---- ---- 99.80 99.29 99.64 99.82 Human faeces contain about 75 per cent of water; and their dry residue was found by Way to have the following composition:--